Acrylonitrile Concentration Research Articles

Suggested interpretation for the anomalous kinetics of acrylonitrile polymerization in homogeneous solution

AbstractThe polymerization in homogeneous solution of acrylonitrile shows an anomalous kinetic behavior. The reaction order in respect to the monomer appears higher than 1, and approaches the order of 2 at low acrylonitrile concentrations (< 2M). This behavior was given various interpretations. No completely satisfactory explanation is, however, available. By taking into account some secondary radical reactions recently discovered (polymerization through CN), a new interpretation of the kinetic anomalous behavior is suggested, and a kinetic model is given which also takes into account the propagation through the triple CN bond.The equations so fully derived justify the experimental results. A reaction order of 2 in respect to the monomer for (AN) tending to zero, and approaching 1 for (AN) > 2M, is deduced from the assumptions made. According to the proposed mechanism, the kinetic deviations from theory do not depend on the initiation rate, as confirmed by experimental results, but only on monomer concentration.

Kinetic Studies on Dimerization of Acrylonitrile by Ruthenium(III) Chloride

In the presence of ruthenium trichloride, acrylonitrile is converted to a mixture of cis- and trans-1, 4-dicyanobutenes, adiponitrile and propionitrile under an atmosphere of hydrogen. The effects of the reaction temperature, RuCl3 concentration, HCl concentration, and partial pressure of hydrogen on the rate of the reaction have been investigated and the results are shown in Figs.3, 4, 5 and 8.The reaction rate was second order in the initial concentration of acrylonitrile as shown in Fig.5. However, the plots of hydrogen absorption vs. reaction time (Figs.2 and 3) indicate that the reaction proceeded independently of the, actylonitrile concentration.The cause of these apparently conflicting results was found to be that the rate is determined by the totol concentration of -C=N (Table 3). The active species as catalyst is suggested to be a ruthenium complex coordinated with two molecules of nitrites. A reaction mechanism based on the kinetic studies is proposed.

Nitrogenase-catalyzed acrylonitrile reductions

Reduction of acrylonitrile is catalyzed by Azotobacter vinelandii nitrogenase (N 2ase); products are propylene, propane, and ammonia but not amines or imines; H 2 evolution occurs concurrently. ATP, Mg ++, and reductant (sodium dithionite) are required. The apparent K m for acrylonitrile is 10–50 mM. Acrylonitrile is a better N 2ase substrate than its saturated analogs propionitrile and acetonitrile. Acrylonitrile reduction is inhibited by N 2 and CO but not by H 2; substrate inhibition occurs at high acrylonitrile concentrations. The partitioning of electron flow through N 2ase between acrylonitrile reduction and H 2 production from H 3O + was directly measured by simultaneous gas chromatographic analyses of hydrocarbons and H 2. The effect of pH, Γ/2, and Na 2S 2O 4 concentrations on partitioning suggests the need for a more specific structure of or additional site on N 2ase for acrylonitrile reduction than for H 2 evolution. D 2O promotes acrylonitrile reduction by increasing the proportion of the total electron flow which reduces acrylonitrile. Neither the binding of acrylonitrile to N 2ase nor the propylene/propane product ratio is significantly affected by D 2O. The isotope effect on acrylonitrile reduction is explained in terms of relative activation energies of fast steps involved in the transfer of electrons to acrylonitrile and to H 2O + or D 3O +. The acrylic double bond shifts during reduction of acrylonitrile to propylene and reduction of the acrylic double bond to propane occurs in ca. 15% of the product. The propylene/propane product ratio shows major sensitivity to pH and ionic strength. Propane formation is suggested to arise from reduction of an allyl-enzyme intermediate or from reduction of acrylonitrile to enzyme-bound propionitrile and subsequent reduction of enzyme-bound propionitrile. Nitrogenase also catalyzes acrylonitrile reduction in vivo. Product ratios are similar in vivo and in vitro and are the best indication of similarity between isolated N 2ase and in vivo N 2ase. Compared with normal molybdenum-containing N 2ase, N 2ase from A. vinelandii cells grown on vanadium in place of molybdenum exhibits a larger apparent K m for acrylonitrile, a less favorable partitioning of electron flow toward acrylonitrile reduction, and a lower propylene/propane product ratio in vitro and in vivo. Molybdenum- and vanadium-containing N 2ases show the same D 2O enhancement of acrylonitrile reduction. In vivo and in vitro results imply a substrate site containing at least molybdenum and a close competition between acrylonitrile and H 3O + for reducing equivalents, and are consistent with a substrate site containing both iron and molybdenum.

Steady‐state kinetics during initial stages of radical bulk polymerization of acrylonitrile

AbstractThe bulk polymerization of acrylonitrile with azobisisobutyronitrile as initiator and FeCl3 as terminator was studied at 60°C. It was found that the reaction proceeds like solution polymerization and does not exhibit the familiar autoacceleration found in bulk polymerizations. It was concluded that a steady‐state condition of growing radical chains exists. Initial rates, to approximately 3% conversion, were measured dilatometrically and were found to be proportional to the ratio of the initiator to terminator concentration, where this ratio is smaller than 3 : 1 and are due to the predominance of the FeCl3 monoradical termination mechanism. On increasing the ratio of initiator to FeCl3, the usual biradical termination mechanism becomes important as well. Assuming that the ratio of propagation constant to termination constant in this work is similar to the knwon ratio in DMF solution, a monomer “effective” concentration in the bulk of about 20% of the nominal concentration of pure acrylonitrile (14.38 mole/l. at 60°C) can be calculated. This result is interpreted by a molecular mechanism for the bulk polymerization of acrylonitrile.

Graft copolymerization of vinyl monomers with modified cotton. II. Grafting of acrylonitrile and methyl methacrylate on acetylated cotton

AbstractCe(IV)‐induced polymerization of acrylonitrile and methyl methacrylate with acetylated cotton having different acetyl contents was investigated. The extent of interaction between the cotton and monomer is dependent upon the acetyl content of the former as well as on the reaction conditions. Increasing the acetyl content caused a significant decrease in the graft yield. Increasing the acrylonitrile concentration was accompanied by a substantial increase in the graft yields. The same effect was found with the initiator up to a certain concentration, but beyond it there was a reversal. The rate of grafting increased by rising the temperature and follow the order 60° > 40° > 30°C. The Ce(IV) consumption during grafting is greater than that consumed during oxidation. The consumption of Ce(IV) by the cellulosic materials was favorably influenced by the concentrations of monomer and initiator, time, and temperature. Rates of grafting and Ce(IV) consumption during oxidation of acetylated cottons having different acetyl contents strongly support the postulated mechanism of grafting using the Ce(IV)–cellulose redox system. Ce(IV) oxidation had practically no effect on the acetyl groups (expressed as per cent combined acetic acid) of the modified cotton.

Preparation of Acrylic Acid

A modified Reppe process for manufacturing acrylic acid (AA) under normal pressure and another method by hydrolysis of acrylonitrile (AN) are reported. I. Modified Reppe process using normal pressure under continous operation.Thier reaction is affected by various factors such as molar ratio, acetylene feeding velocity, reaction temperature, circulation velocity, viz, agitating velocity and so on.The best reaction conditions were as follows : Acetylene feeding velocity : 200 l/hr.Reaction temperature : 40°CCirculation velocity for the reaction mixture : 1, 800 l/hr.Reaction composition : AA/Solvent=1/1 (wt.) Solvents : MEK, MIBKThe yield was about 80%.II. AN hydrolysisThe follwing reactions for conversion of AN into AA were studied.CH2=CHCN+H2SO4+H2O→CH2=CHCONH2·H2SO4CH2=CHCONH2·H2SO4 +H2O→CH2=CHCOOH + NH4HSO41. The first step reaction (formation of acrylamide).AN/sulfuric acid/water=1/1.5/4 (molar ratio) was employed at 12°C for 5 hrs with strring.The yield was about 95%.2. The second step reaction (formation of AA) The hydrolysis of acrylamide was effected by using 6 mol suplementary water per mol of acrylamide at 100°C for 2 hrs with stirring.Over-all yield of AA was about 850.3. KineticsThe apparent activation energy for the hydrolysis of AN was about 11.3 kcal/mol and the reaction was found to be second order in the concentrations of AN and water.

Characterization of styrene–acrylonitrile copolymer by pyrolysis gas chromatography

AbstractSamples of styrene–acrylonitrile (SAN) copolymer of different compositions, molecular weights, block copolymers, and a blend of styrene and acrylonitrile homopolymers were prepared and characterized by the method of pyrolysis gas chromatography. On decomposition of SAN copolymer samples at 645°C, eleven components were identified, the most important of them being styrene, acrylonitrile, and propionitrile. By examination of the pyrolyzate composition during pyrolysis of the SAN copolymer of different compositions, it was established that the propionitrile yield was definitely decreased when the acrylonitrile concentration in copolymer was about 60 mole‐%. Further, from the propionitrile yield, we could distinguish random SAN copolymer from the styrene‐acrylonitrile homopolymer blend, and on the basis of propionitrile yield some information on the molecular structure of the copolymer could be obtained. The styrene yield depends linearly on the copolymer composition. This permits determination of copolymer composition on the basis of the styrene yield. Furthermore, the effects of decomposition temperature and of molecular weight on the yields of styrene and acrylonitrile were examined.

A Mechanistic Approach to the Electrolytic Reductive Dimerization of Acrylonitrile

Abstract The electrolytic reductive dimerization of acrylonitrile was investigated extensively especially in order to obtain some mechanistic information. The essential point of this reaction exists in the selective formation of adiponitrile under relatively wide conditions and this cannot be explained by a normal kinetic treatment based on the reaction scheme which has been accepted as probable. The heterogenuity in acrylonitrile concentration in the reaction system is assumed and the kinetic formulas are modified. This treatment explains the experimental results very satisfactorily. In order to confirm this mechanistic scheme, the effects of temperature, pH and solvents on the yield of reaction products were examined. All the results are consistent with the proposed mechanism.

Copolymers of starch and polyacrylonitrile: The dilution effect

AbstractIn the ceric ammonium nitrate‐initiated graft polymerization of acrylonitrile (AN) with starch, grafting frequencies and molecular weights of grafted polyacrylonitrile changed from 600 anhydroglucose units (AGU)/graft and 120000 to 280 AGU/graft and 36000 when concentrations of starch and AN were varied from 0.27 and 1.20 to 0.023 and 0.235 moles/l. of water, respectively. The influence of variety of starch, size of the starch granules, and reaction time was studied, and possible reasons for the influence of reactant concentration on the composition of the copolymer are considered.

Polarographic Behavior of Tris(2,2′-bipyridine)cobalt(II) and Tris(2,2′-bipyridine)cobalt(III) in Acetonitrile Solutions

Abstract The electrode processes of tris(2,2′-bipyridine)cobalt(II) and tris(2,2′-bipyridine)cobalt(III) complexes at the dropping mercury electrode in acetonitrile solutions have been investigated by the measurement of direct current, alternating current and Kalousek polarograms. The cobalt(II) complex gave a one-step oxidation and a four-step reduction wave and the cobalt (III) complex, a five-step reduction wave, when tetraethylammonium perchlorate was used as supporting electrolyte. The solution containing the cobalt(II) and the cobalt(III) complexes gave a reversible composite wave. The limiting currents of the first two steps named from positive to negative potentials of the reduction wave of the cobalt(II) complex were diffusion-controlled, the first step being of a one-electron reduction process and the second step, of a two-electron reduction process. From the effect of free 2,2′-bipyridine and water on the reduction wave of the cobalt(II) complex and from the Kalousek polarograms, the electrode processes of the first two steps taking place in the presence of a large concentration of free 2,2′-bipyridine were estimated as, [Co(bipy)_3]^2+\oversete\underset-e\ightleftharpoons[Co(bipy)_3]^+\overset2e\underset-2e\ightleftharpoons[Co(bipy)_3]^- The effect of a small concentration of acrylonitrile on the reduction wave of the cobalt(II) complex was studied.

23—GRAFT COPOLYMERIZATION OF ACRYLONITRILE IN WOOL

An improved method of utilizing bis(acetyl acetonato) copperII complexes as catalysts for grafting polyacrylonitrile in wool fibres has been found. The effects of variation of temperature and of the concentrations of copper, acrylonitrile, water, and additional co-catalysts on the grafting rate are described. On the basis of these results, it is suggested that polymerization may be brought about by a combination of ionic and free-radical mechanisms.

Effect of thiourea on the radical polymerization of vinyl monomers. Part I. Polymerization of acrylonitrile with the hydrogen peroxide–thiourea catalyst system

AbstractThe polymerization of acrylonitrile (AN) was studied in aqueous solution with hydrogen peroxide (H2O2) as catalyst and thiourea (TU) as cocatalyst at 30°C. Since the polymerization was carried out at a relatively low temperature, AN was not polymerized by hydrogen peroxide alone. Upon addition of TU to the reaction system, polymerization occurred immediately, and the rate of polymerization increased with increasing TU concentration. In order to obtain the overall polymerization equation, the dependence of polymerization rate on H2O2 and AN concentration was studied kinetically. It was found that the overall polymerization rate Rp was represented by the equation: Rp = K[TU]frac12;[H2O2]frac12;[AN], where K is the rate constant. The acceleration in the presence of TU might be attributed to a redox reaction between H2O2 and TU which would produce free radicals rapidly. The effect of substituents was investigated by use of various N‐substituted derivatives of TU. The polymerization rate increased linearly with the σ* constants of the substituents as electron‐withdrawing substituents were added. The polymerization mechanism is discussed on the basis of the results.

Radiation‐induced copolymerization of acrylonitrile with styrene

AbstractRadiation‐induced copolymerization of acrylonitrile with styrene was carried out over a wide range of temperatures. It was found that the rate of copolymerization is proportional to the square root of the dose rate. An apparent activation energy of 6.90 kcal./mole was obtained for the copolymerization in an equimolar mixture of monomers. The rate of copolymerization increased with the molar concentration of acrylonitrile in the monomer mixture. Monomer reactivity ratios were determined as rAN = 0.03, rSt = 0.33 for the copolymerization at 15 and 0°C., rAN = 0.28, rSt = 0 at −20°C. in the liquid state of monomers. On the other hand, the monomer reactivity ratios were obtained as rAN ≃ 0 and rSt ≃ 0 for the copolymerization in the solid state at −78°C. It was concluded from these experimental results that there is a great difference between the liquid‐state and solid‐state copolymerizations, both in the polymerization mechanism and the structure of copolymers.

Radiation‐induced copolymerization of acrylonitrile with methyl methacrylate

AbstractRadiation‐induced copolymerization of acrylonitrile (1) with methyl methacrylate (2) was investigated over a wide range of temperatures. The rate of copolymerization decreased linearly with the molar concentration of acrylonitrile in the liquid‐state copolymerization at 15°C. On the contrary, the rate of copolymerization increased linearly with the concentration of acrylonitrile in the solid state at −78°C. The rate of copolymerization was proportional to the square root of the dose rate in an equimolar mixture of the monomers at 15°C. The apparent activation energy of the copolymerization was 4.62 kcal./mole in an equimolar mixture of the monomers. Monomer reactivity ratios r1 and r2 were determined from the experiments at various temperatures. From these results, the differences of the activation energies in the propagation steps were obtained as follows: E‡11 − E‡12 = 2.76 kcal./mole; E‡22 − E‡21 = 2.58 kcal./mole.

Electrolytic Reductive Coupling: I . Acrylonitrile

The electrolysis of concentrated solutions of acrylonitrile in aqueous tetraethylammonium p‐toluenesulfonate at lead or mercury cathodes and at controlled pH yields adiponitrile in virtually quantitative yields and at current efficiencies close to 100%. If the catholyte has acrylonitrile concentrations much below 10% or contains alkali metal cations, increasing quantities of propionitrile appear as by‐product. An explanation is offered for this shift in product distribution. Variations in laboratory cell design and supporting electrolyte composition are discussed.

Kinetics of polymerization of vinylidene chloride. IV. Copolymerization of vinylidene chloride and acrylonitrile

AbstractThe emulsion polymerization of vinylidene chloride is divisible into three stages: (I) a normal emulsion polymerization at a rate dependent on the 0.6 power of both the catalyst and surfactant concentration; (II) at a rate less than half that of I; (III) at a rate which increases in direct proportion to the catalyst concentration and independently of surfactant concentration. A careful examination of stirring rate has shown that the slowdown in stage II probably results from monomer starvation caused by slow diffusion of coalesced droplets, and that recovery in stage III is the result of transfer of monomer at the time of collision between a polymer particle and a monomer droplet. Extension of this work to copolymers of vinylidene chloride and acrylonitrile has shown a similar kinetic effect at high ratios of vinylidene chloride. The rate of polymerization for a system containing 90% vinylidene chloride decreases sharply after 15% conversion. The polymer formed increases in acrylonitrile content with conversion, reaches a maximum, and then decreases during stage III of the reaction. A run containing 70% vinylidene chloride in the charge did not show a slowdown but gave evidence of a maximum in the curve relating conversion and composition. At higher acrylonitrile content, no slowing occurred, and the polymer composition changed monotonically with conversion. Since acrylonitrile is partially soluble in water, the partition coefficient of acrylonitrile between vinylidene chloride and water was determined at concentrations similar to those used in the polymerizations. The partition coefficient decreases with increasing acrylonitrile concentration in the water phase. Apparent reactivity ratios were calculated on the basis of the monomer composition corrected for the water solubility of acrylonitrile and the initial composition of the copolymer. These values are r1 = 0.390 and r2 = 0.585, vinylidene chloride being considered to be the first monomer. The existence of a unique reactivity ratio indicates that the composition of the initial polymer is controlled only by the relative reactivities of the comonomers and the water solubility of acrylonitrile. The polymer formed later is also influenced by the rate of transport of vinylidene chloride to the reaction site. This is confirmed by the conversion curves and the manner in which composition changes with conversion.

The electrolytic reduction and sodium reduction‐polymerization of acrylonitrile

AbstractThe reduction of acrylonitrile at mercury electrodes has been studied both polarographically and coulometrically at controlled potential. The half‐wave potential is about 1.6 v. versus a mercury pool both for pure acrylonitrile and for acrylonitrile in dimethylformamide, in the presence and absence of water. As long as water is present the diffusion current is directely proportional to the concentration of acrylonitrile, at least up to 0.2 mg./ml. In the absence of water, reduction of acrylonitrile in dimethylformamide at this potential leads to condensation of reactions initiated by the carbanion. The diffusion current is no longer proportional to the concentration. Comparison of electrolytic‐ and sodium‐reduction products of acrylonitrile gives information about the mechanisms of these reductions and the role of water in the polarographic analysis. A new yellow sodium‐reduction polymer of acrylonitrile is described, and data on the ultraviolet and infrared spectra are presented.

Effectiveness of Mixtures of Acrylonitrile and Carbon Tetrachloride against Three Pests of Stored Corn1

Maize heavily infested with a complex of the rice weevil, Sitophilus oryza (L.) (- Calandra oryzae L.), Sitotroga cerealella (Oliv.), the Angoumois grain moth, and Tribolium castaneum (Hbst.) the red flour beetle, was fumigated with 1: 2, 1 :4, 1:6, and 1: 8, by weight, mixtures of acrylonitrile: carbon tetrachloride at dosages of 0.05, 0.10, and 0.20 ml. of fumigant per 3 liters of grain. Similar maize was fumigated with a 3: 1, by volume, mixture of ethylene dichloride:carbon tetrachloride at a dosage of 0.40 ml. per 3 liters of grain as a standard for comparison. The grain was fumigated for 24 hours. Counts were made of living adults of each species 24 hours and 6 weeks after tire fumigants were applied. The two higher dosages of the 1: 2 mixture and the highest dosage of the other mixtures were considered effective against all three species at the end of 24 hours. Only the highest dosage of the 1: 2 mixture and the standard fumigant were considered satisfactory against the three species at the end of 6 weeks. Indirect evidence of competition between S. oryza and S. cerealella was found. As the low dosages and concentrations of acrylonitrile were not satisfactory, the use of such mixtures as general grain fumigants in Colombia does not appear practical.

Polymerization of acrylonitrile by ceric salt in the presence of starch. Vinyl polymerization. L1.

AbstractA graft copolymer of polyacrylonitrile with starch was obtained by radical polymerization of acrylonitrile in the presence of ceric salt and amylose, accompanied by a considerable amount of homopolymer of acrylonitrile. The rate of polymerization was faster in dimethyl sulfoxide than in water. The following empirical rate equations were presented. equation image where A, B and C are constants and [S], [M] and [TCe4+] are the concentration of starch, acrylonitrile and total ceric compounds respectively. The differences between the two equations were discussed.

Sorption of Single- and Multiple-Component Fumigants by Whole-Kernel Corn under Recirculation, and Correlated Mortality of Stored-Product Insects1

Gas chromatography was used to determine the concentrations of acrylonitrile, carbon disulfide, carbon tetrachloride, chloropicrin, ethylene dibromide, ethylene dichloride, hydrocyanic acid, methyl bromide, and of fumigant mixtures (on a volume basis) of acrylonitrile-carbon tetrachloride (25–75), carbon disulfide-carbon tetrachloride (20–80), ethylene dichloridecarbon tetrachloride (75–25), and carbon tetrachloride-ethylene dichloride-ethylene dibromide (60–35-5), under conditions of no load and of a load of corn (whole-kernel grade No. 2 yellow) under recirculation of fumigant. Mortality of adults of Tribolium confusum Duv. and Sitopkilus oryza (L.) are included.